This invention relates generally to the field of earth-working equipment having a "boom" comprised of at least one lift arm and at least one curling linkage for manipulating a tool or implement. More specifically, the invention relates to improved means for rapidly connecting (attaching) and disconnecting implements to earth-working equipment of this type.
Original equipment manufacturers ("OEMs") of earth-working equipment have used various means for attaching implements to a boom. The most common method of attachment is the insertion of two straight pins (one hinge pin and one link pin) through a set of holes in the implement that can be aligned with corresponding holes in the "lift arm" and "curling linkage" as shown in FIGS. 1a and 1b. This is the typical arrangement currently employed in the industry for connecting earth-working equipment (i.e., an earth-working machine or device) to an implement.
As depicted in FIG. 1a, the primary lift arm is fitted for a hinge pin and the curling linkage is fitted for a link pin. The connection-to an implement, as shown in FIG. 1b, is accomplished and secured by these pins which are inserted into matching holes on each part of the boom and the implement. These pins permit manipulation and rotation of the implement by the lift arm and curling linkage of the boom. The implement is generally lifted by both pins, and is rotated around the hinge pin by the curling linkage to different positions necessary for performing the work function. As its name suggests, the "lift arm" is utilized to bear the major load of raising and lowering the implement, while the "curling linkage" is utilized to rotate the implement about an axis perpendicular to the lift arm. This arrangement is quite versatile and permits the earth-working equipment to usefully employ a number of different implements, such as a hoe bucket, a soil compaction wheel, a hammer, etc. Collectively, the lift arm and the curling linkage are sometimes referred to as the "boom."
For purposes of this patent "implement" means any ancillary or auxiliary piece of equipment, device or tool which can he attached to a loader/backhoe or excavator for the purpose of doing its work and which is configured for connection to the loader/backhoe or excavator using a hinge and link pin or an equivalent system. The implements must he designed so that they can he attached to or disconnected from the boom in a manner that permits full, effective and proper use of the lift arm and curling linkage. Because these implements must be sturdy and durable to perform their functions properly, and since an implement can typically weigh several thousand pounds, the means of connecting the implement to the boom must also be sturdy, durable and secure. Among other things, the method of connection between the earth-working equipment and the implement should be accomplished in a manner that does not distort the forces applied by its use from those intended to otherwise be applied to the boom and the implement. To do so could result in gradual or sudden failure of these parts and resultant damage to property or people.
While the basic method of attachment shown in FIGS. 1a and 1b is sturdy and secure and permits proper operation of the implement, the frequent, but necessary, changing of implements create and magnify other deficiencies that make this an impractical, unsafe and expensive method of attachment.
It is desirable, for economic and other reasons, to have as few pieces of major equipment as possible on a job site at any one time. This objective can only be realized if the equipment that is present can be made versatile enough to handle the variety of jobs necessary on a construction site by use of various implements. When a number of implement changes must be made in the course of a work day, aligning holes between boom and implement and driving pins in and out to make the connection using the system shown in FIG. 1 can become a real problem. It takes significant time, effort, patience and brute force to accomplish the connection in this manner. The hydraulics and controls of earth-working equipment are designed for construction purposes, not for making the slight kinds of movements needed to bring the boom into sufficiently close alignment with the implement to accommodate the closely machined tolerances between the pins and the bushings they must slide through. The alignment of the boom and the implement is especially difficult when the implement and the equipment are on uneven surfaces in different vertical planes, which is usually the case. Similarly, the weight of the implement makes it very difficult to manually assist the alignment of the pin holes in the implement with the bushing holes in the lift arm and curling linkage. Thus, even with the mutual efforts of an equipment operator in the cab and another person on the ground, who attempts to manipulate the heavy implement, it is very difficult to effect the connection of the boom and the implement. Even for persons with the skill and experience necessary, it typically takes twenty to thirty minutes to effect a connection. Multiplied by the number of implement changes that may be required during the course of a work day, particularly on smaller jobs, the lost time can be substantial.
In addition to the time and effort that it takes to make a connection by the traditional method, there is a significant risk of injury for the person on the ground who attempts to facilitate the physical connection. The unattached heavy implement can fall over onto the person, and there is a significant danger of crushing fingers and other body parts between the boom and the implement during the connection or disconnection process. Smashed fingers and hands are a common occurrence.
As shown in FIGS. 1a and 1b, the curling linkage 115 on the boom of most OEM earth-working devices can rotate, i.e., move in relation to the bushing 114 for the hinge pin, to facilitate making the pin-through-hole connections. This arrangement will accommodate different implements with significantly different centerline spacings between their respective hinge and link pins. This does not obviate the problems of connecting and disconnecting an implement to a boom as described previously. In fact, past attempts to find a quick, easy, safe and reliable method of attaching and switching implements have been further frustrated by the failure or unwillingness of the implement manufacturers to standardize on a single spacing between the holes 123 and 133 for the hinge pin and the holes 126 and 136 for the link pins. Although many OEMs of earth-working equipment issue specifications for others to manufacture acceptable tools for their equipment, the specified distance between hinge and link pin varies from OEM to OEM. At the present time, no device is available to solve this problem without either modifying the various implements to a single common spacing between the pins or modifying the implements to a completely different configuration that does not involve pins at all.
The prior art does describe devices that might be generally characterized as "quick couplers". However, none of them solve the foregoing problem of different pin spacings among manufacturers of equipment and implements. For example, U.S. Pat. No. 4,397,604 to McKain describes a device for connecting the boom to an implement with connecting means of the common type shown in FIGS. 1a and 1b. The McKain patent attempts to make it easier to release the implement from the boom. However, release of the implement is always much easier than connection, because it does not require the aforementioned difficult task of aligning machined pins and bushing holes. The McKain device does not make the more difficult connecting process any easier, and it is not "adjustable" as that term is used herein.
In U.S. Pat. No. 4,545,720 to Cochran et al. a device is shown utilizing over-center locking means in an effort to facilitate the connection between an implement and a loader. This device does not relate to implements having holes to accommodate hinge and link pin connections with a hoe boom of the type shown in FIGS. 1a and 1b herein. It shows the use of an over-center locking mechanism to facilitate the process of connecting a pair of loader arms to a tool in a totally different arrangement. Specifically, the overcenter locking mechanism of the Cochran device is used to thrust a wedge shaped appendage on the locking linkage through matching holes in the coupler and the implement, which has been modified by the addition of a "lower inclined bucket ramp." This device functions much the same as the deadbolt on a door. It is not used to apply pressure to the hinge and link pins that are the standard means of connecting an implement to a hoe boom. It does not attempt to, nor would it be possible to, utilize the standard hinge and link pin means of connecting an implement to a hoe boom. Accordingly, it also does not address the problem of different pin spacings contained on implements from different manufacturers.
The Cochran device also has another significant problem. The linkage in the over-center locking mechanism in the Cochran device is used to "push" the wedge into place. In mechanical engineering terms, this linkage is used as a "column" or "strut" having compressive loading applied axially. The strength of the Cochran device is in the columnar strength of this linkage; axial loading of forces sufficient to apply enough pressure to securely grab a pair of implement pins would cause this member to fail as a compressive strut, namely to buckle in a direction perpendicular to its axis.
In the present invention the linkage elements of the locking means are used in "tension," thereby utilizing their full tensile strength, which is much greater than that of the same cross sectional-area used as a compressive strut.
U.S. Pat. No. 4,810,162 to Foster traps two pins at a single, precise, fixed centerline distance apart in two recesses. This device has no means of applying pressure on the pins to keep the connection tight and no adjustment to compensate for wear. As a result, the connection may be tight and secure when the equipment is new, but it soon becomes loose and not secure. A minor deviation in pin spacing should make no difference in the function of an implement. However, it makes all the difference in the world with respect to making an implement connection (attachment) secure, a problem that is particularly true with the Foster device. Also, this device depends on the weight of the implement for its release. There is significant risk of injury when the implement is released because a person must be standing directly behind the implement to insert a special tool into the coupler to effect the release.
Finally, in U.S. Pat. No. 5,082,389 to Belemi another connector is shown which can be utilized to connect a boom with an implement having holes for hinge and link pin connectors. This device utilizes an hydraulic cylinder to close the connection around the link pin. It has the same disadvantages that any hydraulic coupler has. If the hoe boom is not already equipped with the necessary extra hydraulics, they must be added at significant cost over and above that of the connector alone. Also, hydraulics are notorious for their tendency to "bleed off" fluid and pressure against the pin is lost, leaving the implement loose and not securely attached. The operator cannot know from the cab of the earth-working equipment whether he has made a secure connection or not. Moreover, the Belemi device is not adjustable for different pin spacings.